According to a statement from Air Evac Lifeteam, the crash happened at 11:16 p.m. The aircraft and its crew were returning to their base in Manchester, KY after transporting a patient to a hospital in nearby London, KY, approximately 20 miles away.

The helicopter crashed into the parking lot of an elementary school. No patients were on board.

According to the Associated Press, witnesses said there was dense fog in the area at the time of the crash.

"We are devastated at the loss of these crew members who we consider family. We have no details regarding the cause of the accident but will be working with the NTSB in coming days as they conduct their investigation. We thank you all for your messages of support. Please keep these crew members' family and friends and the AEL family in your thoughts and prayers."

The FAA, NTSB and other agencies will investigate the crash.

The company's website states Air Evac Lifeteam has 11 bases in Kentucky.